NEUROSTEROIDS AND ETHANOL INTERACTIONS

描述：（改编自研究者摘要）本研究的目的 建议是探讨内源性的潜在作用 3 α-羟基-5 α-葡聚糖-20-酮（3 α 5 α-THP） 乙醇的电生理和行为作用，包括 乙醇耐受性的发展。我们最近发现乙醇 向大鼠给药产生血浆和脑中的 有效的GABAA受体神经活性类固醇，3 α 5 α-THP， 相关浓度。乙醇对 大脑皮层中的3 α 5 α-THP水平具有时间和剂量依赖性， 足以增强GABAA受体功能。此外，还有一个强大的 酒精睡眠时间与大脑皮质内 3 α 5 α-THP。相比之下，大脑中3 α 5 α-THP的水平没有改变， 因此，在乙醇依赖大鼠中，通过急性乙醇攻击，耐受性可能 研究乙醇对3 α 5 α-THP诱导的影响。损失 乙醇诱导的3 α 5 α-THP水平可能是对 乙醇的药理作用。因此，我们建议测试整体 3 α，5 α-THP介导乙醇药理作用的假说 in vivo. 第一个目标是研究3 α 5 α-THP在行为学中的作用。 以及乙醇的神经生理学效应。3alpha 5alpha-THP的形成将是 预防预处理类固醇生物合成抑制剂和影响 乙醇对神经元放电率的影响，GABAA受体介导的 自发神经元活动、中毒、空中翻正反射和癫痫发作 阈值将被测量。3 α 5 α-THP的作用也将是 在缺乏3 α-羟基类固醇的条件性基因敲除小鼠中研究 淀粉酶-3 α 5 α-THP形成的最后一步。第二个目标将 确定3 α 5 α-THP是否在耐受性的发展中起作用， 使用基因敲除小鼠和类固醇生物合成抑制剂。的 第三个目标将集中在3 α 5 α-THP积累的机制 乙醇给药后。将进行研究，以确定是否 乙醇直接改变3 α 5 α-THP生物合成的活性 内切酶初步结果表明，乙醇可能会增加3 α 5 α-THP 生物合成，而高剂量的乙醇可能会释放或揭露一个“储存”的 3 α 5 α-THP。乙醇对3 α 5 α-THP释放的影响 测量培养的星形胶质细胞。这些研究将探讨 乙醇在快速时间点（秒至分钟），可能与 乙醇的电生理作用。这些研究可能会阐明一个新的 乙醇在中枢神经系统的作用机制，并解释为什么乙醇的影响 对GABA能神经传递的直接影响不能充分解释 乙醇对GABAA受体的作用。这次调查的结果 扩展我们对神经甾体在乙醇作用中的潜在作用的认识 和乙醇耐受性，并可能确定新的因素参与的病因学 酒精中毒

DESCRIPTION: (Adapted from the Investigator's Abstract) The objective of this proposal is to explore the potential role of endogenous 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha5alpha-THP) in the electrophysiological and behavioral actions of ethanol, including the development of ethanol tolerance. We recently discovered that ethanol administration to rats produces an elevation in plasma and brain levels of the potent GABAA receptor neuroactive steroid, 3alpha5alpha-THP, to pharmacologically relevant concentrations. The effects of ethanol on 3alpha5alpha-THP levels in cerebral cortex are time and dose dependent and sufficient to potentiate GABAA receptor function. Moreover, there is a strong correlation between ethanol sleep time and cerebral cortical levels of 3alpha5alpha-THP. In contrast, brain levels of 3alpha5alpha-THP are not altered by acute ethanol challenge in ethanol dependent rats, therefore, tolerance may develop to the effect of ethanol on the induction of 3alpha5alpha-THP. The loss of ethanol induction of 3alpha5alpha-THP levels may underlie tolerance to the pharmacological effects of ethanol. Therefore, we propose to test the overall hypothesis that 3alpha, 5alpha-THP mediates pharmacological effects of ethanol in vivo. The first goal is to investigate the role of 3alpha5alpha-THP in the behavioral and neurophysiological effects of ethanol. 3alpha5alpha-THP formation will be prevented by pretreatment steroid biosynthesis inhibitors and the effects of ethanol on neuronal firing rates, GABAA receptor-mediated inhibition of spontaneous neuronal activity, intoxication, aerial righting reflex and seizure thresholds will be measured. The role of 3alpha 5alpha-THP will also be investigated in conditional knockout mice that lack 3alpha-hydroxysteroid dehydrogenase-the final step in 3alpha5alpha-THP formation. The second aim will determine if 3alpha5alpha-THP plays a role in the development of tolerance to ethanol using both knock out mice and steroid biosynthesis inhibitors. The third aim will focus on the mechanisms of 3alpha5alpha-THP accumulation following ethanol administration. Studies will be conducted to determine if ethanol directly alters the activity of the 3alpha5alpha-THP biosynthetic enzymes. Preliminary results suggest that ethanol may increase 3alpha5alpha-THP biosynthesis, while high dose ethanol may release or uncover a "store" of 3alpha5alpha-THP. The effect of ethanol on 3alpha5alpha-THP release from cultured astrocytes will be measured. These studies will address the effects of ethanol at rapid time points (seconds to minutes) that may be relevant to the electrophysiological actions of ethanol. These studies may elucidate a new mechanism of ethanol action in the CNS and explain why the effects of ethanol on GABAergic neurotransmission could not be adequately explained by the direct action of ethanol at GABAA receptors. The results of this investigation will extend our knowledge of the potential role of neurosteroids in ethanol action and ethanol tolerance and may identify new factors involved in the etiology of alcoholism.